1. Field of the Invention
The present invention relates to an assist grip to be gripped by a passenger getting on means of transportation such as a vehicle, a ship or an airplane to support the passenger""s body, a grip to be gripped to delivery a trunk case or an attachxc3xa9 case, a molding method and molding apparatus of the grip.
The present application is based on Japanese Patent Applications No. 2000-254428 and No. 2001-250713, which are incorporated herein by reference.
2. Description of the Related Art
In general, an assist grip is attached to the left side edge of a ceiling portion of a passenger seat in an automobile for right hand steering in order to maintain safety for a passenger. The assist grip is formed by a lateral elliptic cylindrical grip body molded by a synthetic resin material and an attachment portion molded integrally with both ends by a synthetic resin material. In order to give a soft feeling when gripping the grip body, a leather is bonded to an outer periphery thereof or an outer coating layer is molded by a soft synthetic resin material over the outer periphery of the grip body.
In order to reduce a weight and to prevent a shrinkage cavity from being formed after resin molding, 5 a gas injection molding method has been employed for the assist grip. In the grip molded by the method, a gas injection port 41a is formed in the central part of an elliptic cylindrical grip body 41 and a large hollow portion 41b is formed on the grip body 41 corresponding to the gas injection port 41a as shown in a cross section of FIG. 12 so that the thickness of a resin layer 41c is reduced.
In the conventional grip, the thickness of the resin layer 41c provided in the vicinity of the gas injection port 41a in the grip body 41 is reduced so that a rigidity is deteriorated. Therefore, in the case in which a passenger grips and excessively pulls the grip body 41, there is a possibility that a failure might be caused by stress concentration.
Moreover, in the case in which a soft synthetic resin material is injected and molded over the outer periphery of the grip body 41 to mold an outer coating layer 42 as shown in a chain line of FIG. 12, the rigidity 2 of the grip body 41 is deteriorated as described above so that the gripbody41 is easily deformed by an injection pressure and heat during molding. For this reason, it is necessary to set the range of soft material molding conditions to be reduced and there is also a problem in that productivity cannot be enhanced.
It is an object of the invention to provide a grip capable of solving the problems of the conventional art to enhance a rigidity and capable of enhancing productivity in the case in which an outer coating layer formed of a soft synthetic resin material is to be molded on the outer peripheral surface of a grip body.
It is another object of the invention to provide a method of molding a grip and a molding apparatus which can easily manufacture the grip.
In order to solve the problems described above, a first aspect of the invention is directed to a grip comprising a grip body provided with a resin layer covering a hollow portion formed inside the grip body by gas injection, and a pair of attachment portions formed integrally with both ends of the grip body, wherein a reinforcement portion is formed substantially in a central part in longitudinal direction of the grip body.
A second aspect of the invention is directed to the grip according to the first aspect, wherein the reinforcement portion comprises a pair of concave portions provided on an outer peripheral surface of the resin layer so as to be opposed to each other, a pair of raised portions formed by the concave portions and a thick portion formed on the resin layer having a larger thickness than other portions in the resin layer, thereby reducing a volume of the hollow portions.
A third aspect of the invention is directed to the grip according to the second aspect, wherein the hollow portion is constituted by a first hollow portion formed in a gas injection port side of the hollow portion and bounded with the raised portions and a second hollow portion formed in the opposite side of the hollow portion to the gas injection port, and a spacing W between inner bottom surfaces of the concave portions is set such that a volume of the first hollow portion is substantially larger than a volume of the second hollow portion.
A fourth aspect of the invention is directed to the grip according to the second aspect, wherein a spacing W between inner bottom surfaces of the concave portions is set such that the hollow portion is formed on only the gas injection port side with the raised portions to be a boundary.
A fifth aspect of the invention is directed to the grip according to the second aspect, wherein the concave portions are flat and are formed to have a predetermined length in a longitudinal direction of the grip body.
A fifth aspect of the invention is directed to a method of molding a grip comprising the steps of forming a cavity for a grip body by a mold; providing a resin injection gate and a gas injection gate on a surface of the cavity in a substantially central part of a longitudinal direction of the grip body, the resin injection gate and the gas injection gate being provided at substantially the same position, protruding a plurality of cores into the cavity for molding at least one pair of concave portions, the cores being provided on a position corresponding to the resin injection gate and the gas injection gate; injecting a molten resin into the cavity through the resin injection gate; and injecting a gas into an internal of the molten resin through the gas injection gate, thereby forming hollow portion, raised portions and a thick portion.
A seventh aspect of the invention is directed to a molding device for a grip comprising a mold for forming a cavity; a resin injection gate provided on an inner surface of the mold; a gas injection gate and a resin injection gate provided on the inner surface of the mold 110 and substantially in a central part in a longitudinal direction of the cavity, the gas injection gate and the resin injection gate being provided substantially on the same position; and a plurality of cores for forming at least one pair of concave portions on a grip body, the cores being provided on positions corresponding to the gas injection gate and the resin injection gate.